Lung cancer is predominantly a disease of older adults. Elderly patients however, are less aggressively treated and under-represented in clinical trials. As a consequence, there are several areas of controversy regarding the staging and treatment of these patients. The goal of this proposal is to use national, population-based data to evaluate several issues related to the staging and treatment of elderly patients with advanced non-small cell lung cancer (NSCLC). The specific aims of the study are to: 1) evaluate the relationship between the number of positive lymph nodes and survival of NSCLC patients with N1 disease after adjustment for other prognostic factors;2) assess the effectiveness of postoperative radiotherapy (RT) in elderly patients with completely resected stage III NSCLC with N2 disease;3) determine the role of adjuvant chemotherapy in elderly patients with resected stage III (T4, N0-1) NSCLC;4) evaluate the effectiveness of RT alone for the primary treatment of elderly stage III patients who are not candidates for combined chemoradiation;and 5) assess the prevalence and identify predictors of severe toxicity requiring hospitalization due to chemotherapy and RT in older patients with advanced stage NSCLC treated in the community. To address these Aims, we will use data from the Surveillance, Epidemiology, and End Results (SEER) registry linked to Medicare claims. The study cohort will be comprised of all patients >65 years of age with histologically confirmed advanced stage NSCLC diagnosed between 1991 and 2002. Sociodemographic data and information on the extent of disease at diagnosis will be obtained from SEER. Data on the initial course of treatment (surgery, chemotherapy, and RT) will be ascertained from both SEER and Medicare claims. Linked census data and information from the Area Resource File will be used to obtain information on socioeconomic status and community level factors such as physician availability. Additional information about the treating physicians'characteristics will be obtained from the American Medical Association's Physician Masterfile. The primary outcome of Aims 1 to 4 will be overall survival and the secondary outcome will be lung cancer-specific survival, as assessed by Medicare and SEER data, respectively. The outcome of Aim 5, treatment toxicity, will be ascertained from Medicare claims. Each Aim will be evaluated using unadjusted, stratified, and multivariate analyses to control for other important prognostic factors such as socioeconomic characteristics, physician availability, tumor histology, stage, and comorbidities. Additionally, we will use propensity score methods, sensitivity analysis, and instrumental variable techniques to minimize bias inherent to observational studies. The findings from this project will provide information that can directly impact the care of elderly patients with NSCLC and inform the design of future trials of treatment strategies for advanced lung cancer. PUBLIC HEALTH RELEVANCE: Lung cancer is the most common cause of cancer-related mortality among older adults in the United States. Despite the high incidence of lung cancer and high mortality rates, elderly patients are less likely to be vigorously staged, less aggressively treated, and typically under-represented in clinical trials. This study will provide information regarding the efficacy of several therapies and may help resolve several controversies regarding the staging and treatment of elderly patients with advanced stage lung cancer.